Stringed instruments have been around for thousands of years. Conventionally, a string is placed under longitudinal tension until it vibrates at a pre-determined pitch when plucked, bowed, picked, or otherwise induced to vibrate. String vibration is then amplified through coupling to a resonant structure known as a soundboard, or electronically through a transducer. The coupling mechanism is known as a bridge.
Maintaining accurate pitch has always been a challenge, as the force exerted by multiple strings under tension is quite significant, causing instruments to deform. Instruments must withstand string tension yet be light weight in order to be easily held, played, or transported by musicians. Conventional, instruments are resonant in order to efficiently amplify string vibrations and respond with sensitivity to a player's touch.
Conventional technologies use a front mounted placement. Strings contact a bridge mechanism, and contact is maintained through string direction change (tangential, lateral), relative to the length of the string (longitudinal). Two conventional bridge formats exist, differentiated by string termination points: downward force bridges, and attachment point bridges:
a. Conventional downward force bridges use downward force (tangential, lateral) —against the front of the instrument—to couple the string to the soundboard, with string termination points located independently of the bridge. Longitudinal string tension is redirected tangentially, or laterally. Examples include: violin, cello, archtop guitar, etc.b. Conventional attachment point bridges, terminate strings on the soundboard, either as part of the bridge mechanism, or independently located. Longitudinal string tension is applied directly to the soundboard, either longitudinally, tangentially, or laterally. Examples include: acoustic guitar, electric guitar & bass, etc.
There are significant problems with conventional technologies that include:
a. Both downward force and attachment point bridges restrict soundboard and string vibration due to string tension applied directly to the soundboard: the higher the pitch, for a given string, the greater the tension applied to the soundboard. The greater the tension, the greater the vibrational restriction, for both soundboard and string. Restricted string and soundboard vibration results in reduced musical sensitivity, sustain, and harmonic detail.b. In order to counteract string tension applied to the soundboard, various bracing schemes have been devised. Every form of soundboard bracing adds mass to the soundboard, slowing directional change, and restricting vibrational movement. Additional bracing requires additional material, maintenance and expense, as well as opportunities for joint fatigue or failure.c. Conventional technologies are particularly vulnerable to changes in string tension or environmental temperature and humidity. Because string pitch (tuning and intonation) is directly dependent upon string coupling to the soundboard, any alteration to the geometry or relationship between the string and soundboard interactively affects tuning, intonation, and the structural integrity of the instrument.
There is a need for a bridge mechanism to facilitate vibrational coupling between string and soundboard, yet dissociate—or greatly reduce, in comparison to conventional technologies—longitudinal, tangential, and lateral string tension from the coupling process.
There is a further need for a bridge mechanism that allows the soundboard to be designed in such a manner as to remain independent of the necessity to withstand longitudinal (including tangential and lateral) string tension. Building upon the previous paragraph above, the soundboard can disassociate from structural necessity, i.e., function independently of form, shape, size, configuration, integrity, and design issues related to the remainder of the instrument.
There is also a need for a bridge mechanism to simply adjust the relationship between string and fingerboard, thus affecting playability (force required to fret a note at a given pitch) and intonation, without requiring interactive adjustments to the soundboard, soundboard bracing, or neck (fingerboard) angle in relation to the soundboard or bridge.
There is a need for a bridge mechanism to facilitate soundboard designs that require less structural bracing, thus simplifying construction, maintenance, and reducing mechanical failure opportunities.
There is a need for a bridge mechanism to facilitate soundboard designs that require less mass, thus increasing the directional vibrational responsiveness of the soundboard and enhancing transient detail, overtone, and note articulation amplification.